How to I change the speed of the podcast?

In the current version of the Stitcher app on iOS, from the Now Playing page, tap the ellipsis to the left of the rewind button, or scroll down a little. This will display the playback controller options and give you access to Car Mode, Speed Control (0.5x, 1x, 1.25x, 1.5x, 2x), and the Sleep Timer.

If you tap the Speed Control it will change how fast episodes play until you find the speed you like.